BACKGROUND - The data existing in the literature regarding the safety of using regadenoson with symptom-limited exercise are limited, which motivated the authors to undertake this randomized study.
METHODS - We offered patients scheduled to undergo vasodilator stress nuclear myocardial perfusion imaging the opportunity to exercise instead. Patients who failed to reach target heart rate (THR) were randomized to (1) receive regadenoson at peak exercise or (2) stop exercise and receive regadenoson at rest. Patients who reached THR received a standard Tc-99m sestamibi injection with no regadenoson.
RESULTS - 200 patients were included (66% male, mean age 52.5 ± 13.6). 125 patients (62%) reached THR with exercise alone. All stress protocols were well tolerated, and there were no significant adverse events. There were no statistically significant differences in the extent of perfusion abnormalities, image quality, or rate of referral to cardiac catheterization within 60 days between the groups. In fully adjusted logistic regression models, beta-blocker use and diabetes remained significant univariate predictors of failure to reach THR (OR 0.21, 95% CI 0.1-0.5, P < .0001, OR 0.34, 95% CI 0.2-0.7, P = .004, respectively).
CONCLUSIONS - A protocol combining regadenoson at peak exercise in patients unable to reach THR with exercise is feasible, well-tolerated, and yields comparable imaging results to a standard regadenoson injection at rest. In addition, pharmacologic stress testing may be over-ordered in current clinical practice, as patients referred for such testing were often able to exercise.